The enormous variety of biochemical reactions that comprise life are nearly all mediated by a series of biological catalysts known as enzymes. Enzymes are proteins which possess specific catalytic activities that enable them to catalyze a series of reactions, hence enabling metabolic pathways to degrade and to reconstruct products needed to maintain organisms. By the binding of substrates through geometrically and physically complementary reactions, enzymes are stereospecific in binding substrates as well as in catalyzing reactions. The stringency for this stereospecificity varies as some enzymes are more specific to the identity of their substrates, while others are capable of binding multiple substrates and can catalyze numerous types of reactions.
Examples of enzymes include, for example, protein kinases, methyltransferases, dehydrogenases, reductases, acyltransferases, transferases, ATP-ases, carboxylases, synthases and phosphatases. Such enzymes have the ability to, for example: to reversibly phosphorylate proteins in order to regulate protein activity in eukaryotic cells; to catalyze the transfer of an acyl chain to a lipid precursor; to transfer a carboxyl group from an organic substrate, e.g., bicarbonate to a co-factor, e.g., biotin; to oxidize an alcohol group on a substrate molecule; to reduce a carbonyl group on a substrate molecule; to bind a co-enzyme; to participate in the metabolism of a substrate, e.g., a small molecule substrate, e.g., an alcohol, steroid, or fatty acid molecule; to oxidize an alcohol group on a substrate molecule; to hydrolyze ATP, playing a pivotal role in translating chemically stored energy into biological energy; to be involved in a condensation reaction between acyl and malonyl groups to yield beta-ketoacyl derivatives; to catalyze an acyl-CoA ligase or acetoacetyl-CoA synthetase reaction; to catalyze the hydrolysis of phosphatidylinositol; to associate with ras; to mediate guanine nucleotide exchange activity; as well as many others. Accordingly, there exists a need to identify additional human enzymes, for example, for use as disease markers and as targets for identifying various therapeutic modulators.